Luigi Capogrosso
86 lines
2.7 KiB
C
86 lines
2.7 KiB
C
/// MentOS, The Mentoring Operating system project
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/// @file timer.h
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/// @brief Programmable Interval Timer (PIT) definitions.
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/// @copyright (c) 2019 This file is distributed under the MIT License.
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/// See LICENSE.md for details.
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#pragma once
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#include "kernel.h"
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#include "stdint.h"
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/// @defgroup picregs Programmable Interval Timer Registers
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/// @brief The list of registers used to set the PIT.
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/// @{
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/// Channel 0 data port (read/write).
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#define PIT_DATAREG0 0x40
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/// Channel 1 data port (read/write).
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#define PIT_DATAREG1 0x41
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/// Channel 2 data port (read/write).
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#define PIT_DATAREG2 0x42
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/// Mode/Command register (write only, a read is ignored).
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#define PIT_COMREG 0x43
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/// @}
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/// @brief Frequency divider value (1.193182 MHz).
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#define PIT_DIVISOR 1193180
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/// @brief Command used to configure the PIT.
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/// @details
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/// 0x36 = 00110110B.
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/// Channel | 00 | Select Channel 0.
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/// Access mode | 11 | lobyte/hibyte.
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/// Operating mode | 011 | Mode 3 (square wave generator).
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/// BCD/Binary mode | 0 | 16-bit binary.
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#define PIT_CONFIGURATION 0x36
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#define PIT_MASK 0xFF
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/// @brief Pointer to a functionality to wake up.
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typedef void (*wakeup_callback_t)();
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/// @brief Holds the information about a wake-up functionality.
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typedef struct wakeup_info {
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/// Pointer to the functionality.
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wakeup_callback_t func;
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/// The tick, in the future, when the functionality must be triggered.
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__volatile__ uint32_t wakeup_at_jiffy;
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/// The period in seconds.
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uint32_t period;
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} wakeup_info_t;
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/// @brief Handles the timer.
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/// @details In this case, it's very simple: We
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/// increment the 'timer_ticks' variable every time the
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/// timer fires. By default, the timer fires 18.222 times
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/// per second. Why 18.222Hz? Some engineer at IBM must've
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/// been smoking something funky
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void timer_handler(pt_regs *reg);
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/// @brief Sets up the system clock by installing the timer handler into IRQ0.
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void timer_install();
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/// @brief Returns the number of ticks since the system is running.
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uint64_t timer_get_ticks();
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/// @brief Returns the number of ticks since the system is running.
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uint64_t timer_get_subticks();
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/// @brief Registers a function which will be waken up at each tick.
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/// @param func The functionality which must be triggered.
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/// @param period The period in second.
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void timer_register_wakeup_call(wakeup_callback_t func, uint32_t period);
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/// @brief Makes the process sleep for the given ammount of time.
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/// @param seconds The ammount of seconds.
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void sleep(unsigned int seconds);
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/// @brief Allows to set the timer phase to the given frequency.
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/// @param hz The frequency to set.
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void timer_phase(const uint32_t hz);
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